PR tree-optimization/85699
[official-gcc.git] / gcc / stmt.c
blobb8df18181377a13923000f7f85c0706c7ac08252
1 /* Expands front end tree to back end RTL for GCC
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* This file handles the generation of rtl code from tree structure
21 above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
22 The functions whose names start with `expand_' are called by the
23 expander to generate RTL instructions for various kinds of constructs. */
25 #include "config.h"
26 #include "system.h"
27 #include "coretypes.h"
28 #include "backend.h"
29 #include "target.h"
30 #include "rtl.h"
31 #include "tree.h"
32 #include "gimple.h"
33 #include "cfghooks.h"
34 #include "predict.h"
35 #include "memmodel.h"
36 #include "tm_p.h"
37 #include "optabs.h"
38 #include "regs.h"
39 #include "emit-rtl.h"
40 #include "pretty-print.h"
41 #include "diagnostic-core.h"
43 #include "fold-const.h"
44 #include "varasm.h"
45 #include "stor-layout.h"
46 #include "dojump.h"
47 #include "explow.h"
48 #include "stmt.h"
49 #include "expr.h"
50 #include "langhooks.h"
51 #include "cfganal.h"
52 #include "tree-cfg.h"
53 #include "params.h"
54 #include "dumpfile.h"
55 #include "builtins.h"
58 /* Functions and data structures for expanding case statements. */
60 /* Case label structure, used to hold info on labels within case
61 statements. We handle "range" labels; for a single-value label
62 as in C, the high and low limits are the same.
64 We start with a vector of case nodes sorted in ascending order, and
65 the default label as the last element in the vector.
67 Switch statements are expanded in jump table form.
71 struct simple_case_node
73 simple_case_node (tree low, tree high, tree code_label):
74 m_low (low), m_high (high), m_code_label (code_label)
77 /* Lowest index value for this label. */
78 tree m_low;
79 /* Highest index value for this label. */
80 tree m_high;
81 /* Label to jump to when node matches. */
82 tree m_code_label;
85 extern basic_block label_to_block_fn (struct function *, tree);
87 static bool check_unique_operand_names (tree, tree, tree);
88 static char *resolve_operand_name_1 (char *, tree, tree, tree);
90 /* Return the rtx-label that corresponds to a LABEL_DECL,
91 creating it if necessary. */
93 rtx_insn *
94 label_rtx (tree label)
96 gcc_assert (TREE_CODE (label) == LABEL_DECL);
98 if (!DECL_RTL_SET_P (label))
100 rtx_code_label *r = gen_label_rtx ();
101 SET_DECL_RTL (label, r);
102 if (FORCED_LABEL (label) || DECL_NONLOCAL (label))
103 LABEL_PRESERVE_P (r) = 1;
106 return as_a <rtx_insn *> (DECL_RTL (label));
109 /* As above, but also put it on the forced-reference list of the
110 function that contains it. */
111 rtx_insn *
112 force_label_rtx (tree label)
114 rtx_insn *ref = label_rtx (label);
115 tree function = decl_function_context (label);
117 gcc_assert (function);
119 vec_safe_push (forced_labels, ref);
120 return ref;
123 /* As label_rtx, but ensures (in check build), that returned value is
124 an existing label (i.e. rtx with code CODE_LABEL). */
125 rtx_code_label *
126 jump_target_rtx (tree label)
128 return as_a <rtx_code_label *> (label_rtx (label));
131 /* Add an unconditional jump to LABEL as the next sequential instruction. */
133 void
134 emit_jump (rtx label)
136 do_pending_stack_adjust ();
137 emit_jump_insn (targetm.gen_jump (label));
138 emit_barrier ();
141 /* Handle goto statements and the labels that they can go to. */
143 /* Specify the location in the RTL code of a label LABEL,
144 which is a LABEL_DECL tree node.
146 This is used for the kind of label that the user can jump to with a
147 goto statement, and for alternatives of a switch or case statement.
148 RTL labels generated for loops and conditionals don't go through here;
149 they are generated directly at the RTL level, by other functions below.
151 Note that this has nothing to do with defining label *names*.
152 Languages vary in how they do that and what that even means. */
154 void
155 expand_label (tree label)
157 rtx_code_label *label_r = jump_target_rtx (label);
159 do_pending_stack_adjust ();
160 emit_label (label_r);
161 if (DECL_NAME (label))
162 LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));
164 if (DECL_NONLOCAL (label))
166 expand_builtin_setjmp_receiver (NULL);
167 nonlocal_goto_handler_labels
168 = gen_rtx_INSN_LIST (VOIDmode, label_r,
169 nonlocal_goto_handler_labels);
172 if (FORCED_LABEL (label))
173 vec_safe_push<rtx_insn *> (forced_labels, label_r);
175 if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
176 maybe_set_first_label_num (label_r);
179 /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the
180 OPERAND_NUMth output operand, indexed from zero. There are NINPUTS
181 inputs and NOUTPUTS outputs to this extended-asm. Upon return,
182 *ALLOWS_MEM will be TRUE iff the constraint allows the use of a
183 memory operand. Similarly, *ALLOWS_REG will be TRUE iff the
184 constraint allows the use of a register operand. And, *IS_INOUT
185 will be true if the operand is read-write, i.e., if it is used as
186 an input as well as an output. If *CONSTRAINT_P is not in
187 canonical form, it will be made canonical. (Note that `+' will be
188 replaced with `=' as part of this process.)
190 Returns TRUE if all went well; FALSE if an error occurred. */
192 bool
193 parse_output_constraint (const char **constraint_p, int operand_num,
194 int ninputs, int noutputs, bool *allows_mem,
195 bool *allows_reg, bool *is_inout)
197 const char *constraint = *constraint_p;
198 const char *p;
200 /* Assume the constraint doesn't allow the use of either a register
201 or memory. */
202 *allows_mem = false;
203 *allows_reg = false;
205 /* Allow the `=' or `+' to not be at the beginning of the string,
206 since it wasn't explicitly documented that way, and there is a
207 large body of code that puts it last. Swap the character to
208 the front, so as not to uglify any place else. */
209 p = strchr (constraint, '=');
210 if (!p)
211 p = strchr (constraint, '+');
213 /* If the string doesn't contain an `=', issue an error
214 message. */
215 if (!p)
217 error ("output operand constraint lacks %<=%>");
218 return false;
221 /* If the constraint begins with `+', then the operand is both read
222 from and written to. */
223 *is_inout = (*p == '+');
225 /* Canonicalize the output constraint so that it begins with `='. */
226 if (p != constraint || *is_inout)
228 char *buf;
229 size_t c_len = strlen (constraint);
231 if (p != constraint)
232 warning (0, "output constraint %qc for operand %d "
233 "is not at the beginning",
234 *p, operand_num);
236 /* Make a copy of the constraint. */
237 buf = XALLOCAVEC (char, c_len + 1);
238 strcpy (buf, constraint);
239 /* Swap the first character and the `=' or `+'. */
240 buf[p - constraint] = buf[0];
241 /* Make sure the first character is an `='. (Until we do this,
242 it might be a `+'.) */
243 buf[0] = '=';
244 /* Replace the constraint with the canonicalized string. */
245 *constraint_p = ggc_alloc_string (buf, c_len);
246 constraint = *constraint_p;
249 /* Loop through the constraint string. */
250 for (p = constraint + 1; *p; )
252 switch (*p)
254 case '+':
255 case '=':
256 error ("operand constraint contains incorrectly positioned "
257 "%<+%> or %<=%>");
258 return false;
260 case '%':
261 if (operand_num + 1 == ninputs + noutputs)
263 error ("%<%%%> constraint used with last operand");
264 return false;
266 break;
268 case '?': case '!': case '*': case '&': case '#':
269 case '$': case '^':
270 case 'E': case 'F': case 'G': case 'H':
271 case 's': case 'i': case 'n':
272 case 'I': case 'J': case 'K': case 'L': case 'M':
273 case 'N': case 'O': case 'P': case ',':
274 break;
276 case '0': case '1': case '2': case '3': case '4':
277 case '5': case '6': case '7': case '8': case '9':
278 case '[':
279 error ("matching constraint not valid in output operand");
280 return false;
282 case '<': case '>':
283 /* ??? Before flow, auto inc/dec insns are not supposed to exist,
284 excepting those that expand_call created. So match memory
285 and hope. */
286 *allows_mem = true;
287 break;
289 case 'g': case 'X':
290 *allows_reg = true;
291 *allows_mem = true;
292 break;
294 default:
295 if (!ISALPHA (*p))
296 break;
297 enum constraint_num cn = lookup_constraint (p);
298 if (reg_class_for_constraint (cn) != NO_REGS
299 || insn_extra_address_constraint (cn))
300 *allows_reg = true;
301 else if (insn_extra_memory_constraint (cn))
302 *allows_mem = true;
303 else
304 insn_extra_constraint_allows_reg_mem (cn, allows_reg, allows_mem);
305 break;
308 for (size_t len = CONSTRAINT_LEN (*p, p); len; len--, p++)
309 if (*p == '\0')
310 break;
313 return true;
316 /* Similar, but for input constraints. */
318 bool
319 parse_input_constraint (const char **constraint_p, int input_num,
320 int ninputs, int noutputs, int ninout,
321 const char * const * constraints,
322 bool *allows_mem, bool *allows_reg)
324 const char *constraint = *constraint_p;
325 const char *orig_constraint = constraint;
326 size_t c_len = strlen (constraint);
327 size_t j;
328 bool saw_match = false;
330 /* Assume the constraint doesn't allow the use of either
331 a register or memory. */
332 *allows_mem = false;
333 *allows_reg = false;
335 /* Make sure constraint has neither `=', `+', nor '&'. */
337 for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
338 switch (constraint[j])
340 case '+': case '=': case '&':
341 if (constraint == orig_constraint)
343 error ("input operand constraint contains %qc", constraint[j]);
344 return false;
346 break;
348 case '%':
349 if (constraint == orig_constraint
350 && input_num + 1 == ninputs - ninout)
352 error ("%<%%%> constraint used with last operand");
353 return false;
355 break;
357 case '<': case '>':
358 case '?': case '!': case '*': case '#':
359 case '$': case '^':
360 case 'E': case 'F': case 'G': case 'H':
361 case 's': case 'i': case 'n':
362 case 'I': case 'J': case 'K': case 'L': case 'M':
363 case 'N': case 'O': case 'P': case ',':
364 break;
366 /* Whether or not a numeric constraint allows a register is
367 decided by the matching constraint, and so there is no need
368 to do anything special with them. We must handle them in
369 the default case, so that we don't unnecessarily force
370 operands to memory. */
371 case '0': case '1': case '2': case '3': case '4':
372 case '5': case '6': case '7': case '8': case '9':
374 char *end;
375 unsigned long match;
377 saw_match = true;
379 match = strtoul (constraint + j, &end, 10);
380 if (match >= (unsigned long) noutputs)
382 error ("matching constraint references invalid operand number");
383 return false;
386 /* Try and find the real constraint for this dup. Only do this
387 if the matching constraint is the only alternative. */
388 if (*end == '\0'
389 && (j == 0 || (j == 1 && constraint[0] == '%')))
391 constraint = constraints[match];
392 *constraint_p = constraint;
393 c_len = strlen (constraint);
394 j = 0;
395 /* ??? At the end of the loop, we will skip the first part of
396 the matched constraint. This assumes not only that the
397 other constraint is an output constraint, but also that
398 the '=' or '+' come first. */
399 break;
401 else
402 j = end - constraint;
403 /* Anticipate increment at end of loop. */
404 j--;
406 /* Fall through. */
408 case 'g': case 'X':
409 *allows_reg = true;
410 *allows_mem = true;
411 break;
413 default:
414 if (! ISALPHA (constraint[j]))
416 error ("invalid punctuation %qc in constraint", constraint[j]);
417 return false;
419 enum constraint_num cn = lookup_constraint (constraint + j);
420 if (reg_class_for_constraint (cn) != NO_REGS
421 || insn_extra_address_constraint (cn))
422 *allows_reg = true;
423 else if (insn_extra_memory_constraint (cn)
424 || insn_extra_special_memory_constraint (cn))
425 *allows_mem = true;
426 else
427 insn_extra_constraint_allows_reg_mem (cn, allows_reg, allows_mem);
428 break;
431 if (saw_match && !*allows_reg)
432 warning (0, "matching constraint does not allow a register");
434 return true;
437 /* Return DECL iff there's an overlap between *REGS and DECL, where DECL
438 can be an asm-declared register. Called via walk_tree. */
440 static tree
441 decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED,
442 void *data)
444 tree decl = *declp;
445 const HARD_REG_SET *const regs = (const HARD_REG_SET *) data;
447 if (VAR_P (decl))
449 if (DECL_HARD_REGISTER (decl)
450 && REG_P (DECL_RTL (decl))
451 && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
453 rtx reg = DECL_RTL (decl);
455 if (overlaps_hard_reg_set_p (*regs, GET_MODE (reg), REGNO (reg)))
456 return decl;
458 walk_subtrees = 0;
460 else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL)
461 walk_subtrees = 0;
462 return NULL_TREE;
465 /* If there is an overlap between *REGS and DECL, return the first overlap
466 found. */
467 tree
468 tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs)
470 return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL);
474 /* A subroutine of expand_asm_operands. Check that all operand names
475 are unique. Return true if so. We rely on the fact that these names
476 are identifiers, and so have been canonicalized by get_identifier,
477 so all we need are pointer comparisons. */
479 static bool
480 check_unique_operand_names (tree outputs, tree inputs, tree labels)
482 tree i, j, i_name = NULL_TREE;
484 for (i = outputs; i ; i = TREE_CHAIN (i))
486 i_name = TREE_PURPOSE (TREE_PURPOSE (i));
487 if (! i_name)
488 continue;
490 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
491 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
492 goto failure;
495 for (i = inputs; i ; i = TREE_CHAIN (i))
497 i_name = TREE_PURPOSE (TREE_PURPOSE (i));
498 if (! i_name)
499 continue;
501 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
502 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
503 goto failure;
504 for (j = outputs; j ; j = TREE_CHAIN (j))
505 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
506 goto failure;
509 for (i = labels; i ; i = TREE_CHAIN (i))
511 i_name = TREE_PURPOSE (i);
512 if (! i_name)
513 continue;
515 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
516 if (simple_cst_equal (i_name, TREE_PURPOSE (j)))
517 goto failure;
518 for (j = inputs; j ; j = TREE_CHAIN (j))
519 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
520 goto failure;
523 return true;
525 failure:
526 error ("duplicate asm operand name %qs", TREE_STRING_POINTER (i_name));
527 return false;
530 /* Resolve the names of the operands in *POUTPUTS and *PINPUTS to numbers,
531 and replace the name expansions in STRING and in the constraints to
532 those numbers. This is generally done in the front end while creating
533 the ASM_EXPR generic tree that eventually becomes the GIMPLE_ASM. */
535 tree
536 resolve_asm_operand_names (tree string, tree outputs, tree inputs, tree labels)
538 char *buffer;
539 char *p;
540 const char *c;
541 tree t;
543 check_unique_operand_names (outputs, inputs, labels);
545 /* Substitute [<name>] in input constraint strings. There should be no
546 named operands in output constraints. */
547 for (t = inputs; t ; t = TREE_CHAIN (t))
549 c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
550 if (strchr (c, '[') != NULL)
552 p = buffer = xstrdup (c);
553 while ((p = strchr (p, '[')) != NULL)
554 p = resolve_operand_name_1 (p, outputs, inputs, NULL);
555 TREE_VALUE (TREE_PURPOSE (t))
556 = build_string (strlen (buffer), buffer);
557 free (buffer);
561 /* Now check for any needed substitutions in the template. */
562 c = TREE_STRING_POINTER (string);
563 while ((c = strchr (c, '%')) != NULL)
565 if (c[1] == '[')
566 break;
567 else if (ISALPHA (c[1]) && c[2] == '[')
568 break;
569 else
571 c += 1 + (c[1] == '%');
572 continue;
576 if (c)
578 /* OK, we need to make a copy so we can perform the substitutions.
579 Assume that we will not need extra space--we get to remove '['
580 and ']', which means we cannot have a problem until we have more
581 than 999 operands. */
582 buffer = xstrdup (TREE_STRING_POINTER (string));
583 p = buffer + (c - TREE_STRING_POINTER (string));
585 while ((p = strchr (p, '%')) != NULL)
587 if (p[1] == '[')
588 p += 1;
589 else if (ISALPHA (p[1]) && p[2] == '[')
590 p += 2;
591 else
593 p += 1 + (p[1] == '%');
594 continue;
597 p = resolve_operand_name_1 (p, outputs, inputs, labels);
600 string = build_string (strlen (buffer), buffer);
601 free (buffer);
604 return string;
607 /* A subroutine of resolve_operand_names. P points to the '[' for a
608 potential named operand of the form [<name>]. In place, replace
609 the name and brackets with a number. Return a pointer to the
610 balance of the string after substitution. */
612 static char *
613 resolve_operand_name_1 (char *p, tree outputs, tree inputs, tree labels)
615 char *q;
616 int op;
617 tree t;
619 /* Collect the operand name. */
620 q = strchr (++p, ']');
621 if (!q)
623 error ("missing close brace for named operand");
624 return strchr (p, '\0');
626 *q = '\0';
628 /* Resolve the name to a number. */
629 for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
631 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
632 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
633 goto found;
635 for (t = inputs; t ; t = TREE_CHAIN (t), op++)
637 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
638 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
639 goto found;
641 for (t = labels; t ; t = TREE_CHAIN (t), op++)
643 tree name = TREE_PURPOSE (t);
644 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
645 goto found;
648 error ("undefined named operand %qs", identifier_to_locale (p));
649 op = 0;
651 found:
652 /* Replace the name with the number. Unfortunately, not all libraries
653 get the return value of sprintf correct, so search for the end of the
654 generated string by hand. */
655 sprintf (--p, "%d", op);
656 p = strchr (p, '\0');
658 /* Verify the no extra buffer space assumption. */
659 gcc_assert (p <= q);
661 /* Shift the rest of the buffer down to fill the gap. */
662 memmove (p, q + 1, strlen (q + 1) + 1);
664 return p;
668 /* Generate RTL to return directly from the current function.
669 (That is, we bypass any return value.) */
671 void
672 expand_naked_return (void)
674 rtx_code_label *end_label;
676 clear_pending_stack_adjust ();
677 do_pending_stack_adjust ();
679 end_label = naked_return_label;
680 if (end_label == 0)
681 end_label = naked_return_label = gen_label_rtx ();
683 emit_jump (end_label);
686 /* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. PROB
687 is the probability of jumping to LABEL. */
688 static void
689 do_jump_if_equal (machine_mode mode, rtx op0, rtx op1, rtx_code_label *label,
690 int unsignedp, profile_probability prob)
692 do_compare_rtx_and_jump (op0, op1, EQ, unsignedp, mode,
693 NULL_RTX, NULL, label, prob);
696 /* Return the sum of probabilities of outgoing edges of basic block BB. */
698 static profile_probability
699 get_outgoing_edge_probs (basic_block bb)
701 edge e;
702 edge_iterator ei;
703 profile_probability prob_sum = profile_probability::never ();
704 if (!bb)
705 return profile_probability::never ();
706 FOR_EACH_EDGE (e, ei, bb->succs)
707 prob_sum += e->probability;
708 return prob_sum;
711 /* Computes the conditional probability of jumping to a target if the branch
712 instruction is executed.
713 TARGET_PROB is the estimated probability of jumping to a target relative
714 to some basic block BB.
715 BASE_PROB is the probability of reaching the branch instruction relative
716 to the same basic block BB. */
718 static inline profile_probability
719 conditional_probability (profile_probability target_prob,
720 profile_probability base_prob)
722 return target_prob / base_prob;
725 /* Generate a dispatch tabler, switching on INDEX_EXPR and jumping to
726 one of the labels in CASE_LIST or to the DEFAULT_LABEL.
727 MINVAL, MAXVAL, and RANGE are the extrema and range of the case
728 labels in CASE_LIST. STMT_BB is the basic block containing the statement.
730 First, a jump insn is emitted. First we try "casesi". If that
731 fails, try "tablejump". A target *must* have one of them (or both).
733 Then, a table with the target labels is emitted.
735 The process is unaware of the CFG. The caller has to fix up
736 the CFG itself. This is done in cfgexpand.c. */
738 static void
739 emit_case_dispatch_table (tree index_expr, tree index_type,
740 auto_vec<simple_case_node> &case_list,
741 rtx default_label,
742 edge default_edge, tree minval, tree maxval,
743 tree range, basic_block stmt_bb)
745 int i, ncases;
746 rtx *labelvec;
747 rtx_insn *fallback_label = label_rtx (case_list[0].m_code_label);
748 rtx_code_label *table_label = gen_label_rtx ();
749 bool has_gaps = false;
750 profile_probability default_prob = default_edge ? default_edge->probability
751 : profile_probability::never ();
752 profile_probability base = get_outgoing_edge_probs (stmt_bb);
753 bool try_with_tablejump = false;
755 profile_probability new_default_prob = conditional_probability (default_prob,
756 base);
758 if (! try_casesi (index_type, index_expr, minval, range,
759 table_label, default_label, fallback_label,
760 new_default_prob))
762 /* Index jumptables from zero for suitable values of minval to avoid
763 a subtraction. For the rationale see:
764 "http://gcc.gnu.org/ml/gcc-patches/2001-10/msg01234.html". */
765 if (optimize_insn_for_speed_p ()
766 && compare_tree_int (minval, 0) > 0
767 && compare_tree_int (minval, 3) < 0)
769 minval = build_int_cst (index_type, 0);
770 range = maxval;
771 has_gaps = true;
773 try_with_tablejump = true;
776 /* Get table of labels to jump to, in order of case index. */
778 ncases = tree_to_shwi (range) + 1;
779 labelvec = XALLOCAVEC (rtx, ncases);
780 memset (labelvec, 0, ncases * sizeof (rtx));
782 for (unsigned j = 0; j < case_list.length (); j++)
784 simple_case_node *n = &case_list[j];
785 /* Compute the low and high bounds relative to the minimum
786 value since that should fit in a HOST_WIDE_INT while the
787 actual values may not. */
788 HOST_WIDE_INT i_low
789 = tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type,
790 n->m_low, minval));
791 HOST_WIDE_INT i_high
792 = tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type,
793 n->m_high, minval));
794 HOST_WIDE_INT i;
796 for (i = i_low; i <= i_high; i ++)
797 labelvec[i]
798 = gen_rtx_LABEL_REF (Pmode, label_rtx (n->m_code_label));
801 /* The dispatch table may contain gaps, including at the beginning of
802 the table if we tried to avoid the minval subtraction. We fill the
803 dispatch table slots associated with the gaps with the default case label.
804 However, in the event the default case is unreachable, we then use
805 any label from one of the case statements. */
806 rtx gap_label = (default_label) ? default_label : fallback_label;
808 for (i = 0; i < ncases; i++)
809 if (labelvec[i] == 0)
811 has_gaps = true;
812 labelvec[i] = gen_rtx_LABEL_REF (Pmode, gap_label);
815 if (has_gaps && default_label)
817 /* There is at least one entry in the jump table that jumps
818 to default label. The default label can either be reached
819 through the indirect jump or the direct conditional jump
820 before that. Split the probability of reaching the
821 default label among these two jumps. */
822 new_default_prob
823 = conditional_probability (default_prob.apply_scale (1, 2), base);
824 default_prob = default_prob.apply_scale (1, 2);
825 base -= default_prob;
827 else
829 base -= default_prob;
830 default_prob = profile_probability::never ();
833 if (default_edge)
834 default_edge->probability = default_prob;
836 /* We have altered the probability of the default edge. So the probabilities
837 of all other edges need to be adjusted so that it sums up to
838 REG_BR_PROB_BASE. */
839 if (base > profile_probability::never ())
841 edge e;
842 edge_iterator ei;
843 FOR_EACH_EDGE (e, ei, stmt_bb->succs)
844 e->probability /= base;
847 if (try_with_tablejump)
849 bool ok = try_tablejump (index_type, index_expr, minval, range,
850 table_label, default_label, new_default_prob);
851 gcc_assert (ok);
853 /* Output the table. */
854 emit_label (table_label);
856 if (CASE_VECTOR_PC_RELATIVE
857 || (flag_pic && targetm.asm_out.generate_pic_addr_diff_vec ()))
858 emit_jump_table_data (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
859 gen_rtx_LABEL_REF (Pmode,
860 table_label),
861 gen_rtvec_v (ncases, labelvec),
862 const0_rtx, const0_rtx));
863 else
864 emit_jump_table_data (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
865 gen_rtvec_v (ncases, labelvec)));
867 /* Record no drop-through after the table. */
868 emit_barrier ();
871 /* Terminate a case Ada or switch (C) statement
872 in which ORIG_INDEX is the expression to be tested.
873 If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
874 type as given in the source before any compiler conversions.
875 Generate the code to test it and jump to the right place. */
877 void
878 expand_case (gswitch *stmt)
880 tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE;
881 rtx_code_label *default_label;
882 unsigned int count;
883 int i;
884 int ncases = gimple_switch_num_labels (stmt);
885 tree index_expr = gimple_switch_index (stmt);
886 tree index_type = TREE_TYPE (index_expr);
887 tree elt;
888 basic_block bb = gimple_bb (stmt);
890 auto_vec<simple_case_node> case_list;
892 /* An ERROR_MARK occurs for various reasons including invalid data type.
893 ??? Can this still happen, with GIMPLE and all? */
894 if (index_type == error_mark_node)
895 return;
897 /* cleanup_tree_cfg removes all SWITCH_EXPR with their index
898 expressions being INTEGER_CST. */
899 gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
901 /* Optimization of switch statements with only one label has already
902 occurred, so we should never see them at this point. */
903 gcc_assert (ncases > 1);
905 do_pending_stack_adjust ();
907 /* Find the default case target label. */
908 tree default_lab = CASE_LABEL (gimple_switch_default_label (stmt));
909 default_label = jump_target_rtx (default_lab);
910 basic_block default_bb = label_to_block_fn (cfun, default_lab);
911 edge default_edge = find_edge (bb, default_bb);
913 /* Get upper and lower bounds of case values. */
914 elt = gimple_switch_label (stmt, 1);
915 minval = fold_convert (index_type, CASE_LOW (elt));
916 elt = gimple_switch_label (stmt, ncases - 1);
917 if (CASE_HIGH (elt))
918 maxval = fold_convert (index_type, CASE_HIGH (elt));
919 else
920 maxval = fold_convert (index_type, CASE_LOW (elt));
922 /* Compute span of values. */
923 range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);
925 /* Listify the labels queue and gather some numbers to decide
926 how to expand this switch(). */
927 count = 0;
929 for (i = ncases - 1; i >= 1; --i)
931 elt = gimple_switch_label (stmt, i);
932 tree low = CASE_LOW (elt);
933 gcc_assert (low);
934 tree high = CASE_HIGH (elt);
935 gcc_assert (! high || tree_int_cst_lt (low, high));
936 tree lab = CASE_LABEL (elt);
938 /* Count the elements.
939 A range counts double, since it requires two compares. */
940 count++;
941 if (high)
942 count++;
944 /* The bounds on the case range, LOW and HIGH, have to be converted
945 to case's index type TYPE. Note that the original type of the
946 case index in the source code is usually "lost" during
947 gimplification due to type promotion, but the case labels retain the
948 original type. Make sure to drop overflow flags. */
949 low = fold_convert (index_type, low);
950 if (TREE_OVERFLOW (low))
951 low = wide_int_to_tree (index_type, wi::to_wide (low));
953 /* The canonical from of a case label in GIMPLE is that a simple case
954 has an empty CASE_HIGH. For the casesi and tablejump expanders,
955 the back ends want simple cases to have high == low. */
956 if (! high)
957 high = low;
958 high = fold_convert (index_type, high);
959 if (TREE_OVERFLOW (high))
960 high = wide_int_to_tree (index_type, wi::to_wide (high));
962 case_list.safe_push (simple_case_node (low, high, lab));
965 /* cleanup_tree_cfg removes all SWITCH_EXPR with a single
966 destination, such as one with a default case only.
967 It also removes cases that are out of range for the switch
968 type, so we should never get a zero here. */
969 gcc_assert (count > 0);
971 rtx_insn *before_case = get_last_insn ();
973 /* Decide how to expand this switch.
974 The two options at this point are a dispatch table (casesi or
975 tablejump) or a decision tree. */
978 /* If the default case is unreachable, then set default_label to NULL
979 so that we omit the range check when generating the dispatch table.
980 We also remove the edge to the unreachable default case. The block
981 itself will be automatically removed later. */
982 if (EDGE_COUNT (default_edge->dest->succs) == 0
983 && gimple_seq_unreachable_p (bb_seq (default_edge->dest)))
985 default_label = NULL;
986 remove_edge (default_edge);
987 default_edge = NULL;
989 emit_case_dispatch_table (index_expr, index_type,
990 case_list, default_label, default_edge,
991 minval, maxval, range, bb);
994 reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case);
996 free_temp_slots ();
999 /* Expand the dispatch to a short decrement chain if there are few cases
1000 to dispatch to. Likewise if neither casesi nor tablejump is available,
1001 or if flag_jump_tables is set. Otherwise, expand as a casesi or a
1002 tablejump. The index mode is always the mode of integer_type_node.
1003 Trap if no case matches the index.
1005 DISPATCH_INDEX is the index expression to switch on. It should be a
1006 memory or register operand.
1008 DISPATCH_TABLE is a set of case labels. The set should be sorted in
1009 ascending order, be contiguous, starting with value 0, and contain only
1010 single-valued case labels. */
1012 void
1013 expand_sjlj_dispatch_table (rtx dispatch_index,
1014 vec<tree> dispatch_table)
1016 tree index_type = integer_type_node;
1017 machine_mode index_mode = TYPE_MODE (index_type);
1019 int ncases = dispatch_table.length ();
1021 do_pending_stack_adjust ();
1022 rtx_insn *before_case = get_last_insn ();
1024 /* Expand as a decrement-chain if there are 5 or fewer dispatch
1025 labels. This covers more than 98% of the cases in libjava,
1026 and seems to be a reasonable compromise between the "old way"
1027 of expanding as a decision tree or dispatch table vs. the "new
1028 way" with decrement chain or dispatch table. */
1029 if (dispatch_table.length () <= 5
1030 || (!targetm.have_casesi () && !targetm.have_tablejump ())
1031 || !flag_jump_tables)
1033 /* Expand the dispatch as a decrement chain:
1035 "switch(index) {case 0: do_0; case 1: do_1; ...; case N: do_N;}"
1039 if (index == 0) do_0; else index--;
1040 if (index == 0) do_1; else index--;
1042 if (index == 0) do_N; else index--;
1044 This is more efficient than a dispatch table on most machines.
1045 The last "index--" is redundant but the code is trivially dead
1046 and will be cleaned up by later passes. */
1047 rtx index = copy_to_mode_reg (index_mode, dispatch_index);
1048 rtx zero = CONST0_RTX (index_mode);
1049 for (int i = 0; i < ncases; i++)
1051 tree elt = dispatch_table[i];
1052 rtx_code_label *lab = jump_target_rtx (CASE_LABEL (elt));
1053 do_jump_if_equal (index_mode, index, zero, lab, 0,
1054 profile_probability::uninitialized ());
1055 force_expand_binop (index_mode, sub_optab,
1056 index, CONST1_RTX (index_mode),
1057 index, 0, OPTAB_DIRECT);
1060 else
1062 /* Similar to expand_case, but much simpler. */
1063 auto_vec<simple_case_node> case_list;
1064 tree index_expr = make_tree (index_type, dispatch_index);
1065 tree minval = build_int_cst (index_type, 0);
1066 tree maxval = CASE_LOW (dispatch_table.last ());
1067 tree range = maxval;
1068 rtx_code_label *default_label = gen_label_rtx ();
1070 for (int i = ncases - 1; i >= 0; --i)
1072 tree elt = dispatch_table[i];
1073 tree high = CASE_HIGH (elt);
1074 if (high == NULL_TREE)
1075 high = CASE_LOW (elt);
1076 case_list.safe_push (simple_case_node (CASE_LOW (elt), high,
1077 CASE_LABEL (elt)));
1080 emit_case_dispatch_table (index_expr, index_type,
1081 case_list, default_label, NULL,
1082 minval, maxval, range,
1083 BLOCK_FOR_INSN (before_case));
1084 emit_label (default_label);
1087 /* Dispatching something not handled? Trap! */
1088 expand_builtin_trap ();
1090 reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case);
1092 free_temp_slots ();